Power generator, timepiece and electronic device having the same, and cogging torque adjustment method for the same

• US 6,879,068 B2
• Filed: 02/06/2003
• Issued: 04/12/2005
• Est. Priority Date: 01/06/2000
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Matsuzawa, Kinya
• Primary Examiner(s): Lam, Thanh
• Application Number:
  US10/361,164
• Publication Number:
  US 20030127919A1
• Time in Patent Office: 796 Days
• Field of Search: 310/49.R, 310/254, 310/36, 310/15, 368/157, 368/160, 368/162, 368/163, 368/202, 368/203, 368/204
• US Class Current: 310/49.32
• CPC Class Codes: G04C 10/00 Arrangements of electric power supplies in time pieces circuits G04G19/00; mounting, assembling of components of electromechanical watches G04C3/008, of electronic watches G04G17/00
• CPC Class Codes: H02K 21/185 with the axis of the rotor perpendicular to the plane of the armature
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine

Abstract

Protrusions (260) for adjusting the cogging torque of a rotor (21) are formed on a stator (22) in a small-size power generator (20). Since the protrusions (260) are formed on an inner periphery of a rotor accommodation hole (230) within an angular range of ±45° around a magnetic flux direction of a first magnetic circuit (100) having a smaller magnetic reluctance at a rotation center of the rotor (21), the cogging torque can be effectively reduced. Accordingly, even when the size of components such as an oscillating weight and a power spring is reduced for making a thin timepiece, rotation startability of the rotor can be improved, thus improving power generation efficiency of the small-size power generator.

Claims

1. A power generator comprising:

a rotor having a permanent magnet rotated by a transmitted rotary drive force;

a stator having a rotor accommodation hole, the rotor being disposed in the accommodation hole;

a magnetic core, and a power-generating coil wound around the magnetic core, the magnetic core, atator and rotor constituting a first magnetic circuit, and a part of the stator around and adjacent to the rotor constituting a second magnetic circuit; and

further comprising a protrusion projecting toward the rotor formed on the inner periphery of the rotor accommodation hole of the stator within an angular range of ±

45°

around a magnetic flux direction of the first magnetic circuit at a rotation center of the rotor.

2. The power generator according to claim 1, wherein the protrusion is formed within an angular range of ±

10°

around the magnetic flux direction of the first magnetic circuit at the rotation center of the rotor.

3. The power generator according to claim 2, wherein the protrusion is formed in the magnetic flux direction of the first magnetic circuit at the rotation center of the rotor.

4. The power generator according to claim 1, further comprising an oscillating weight, and a power-generating gear train that provides said transmitted rotary drive force to the rotor by transmitting a rotation of the oscillating weight.

5. A timepiece comprising:

a power generator comprising;

a rotor having a permanent magnet rotated by a transmitted rotary drive force;

a stator having a rotor accommodation hole, the rotor being disposed in the accommodation hole;

a magnetic core, and a power-generating coil wound around the magnetic core, the magnetic core, stator and rotor constituting a first magnetic circuit, and a part of the stator around and adjacent to the rotor constituting a second magnetic circuit; and

further comprising a protrusion projecting toward the rotor formed on the inner periphery of the rotor accommodation hole of the stator within an angular range of ±

45°

around a magnetic flux direction of the first magnetic circuit at a rotation center of the rotor;

a time display; and

a processor for actuating said time display by an electric energy generated by the power generator.

6. An electronic device comprising:

a power generator comprising;

a rotor having a permanent magnet rotated by a transmitted rotary drive force;

a stator having a rotor accommodation hole, the rotor being disposed in the accommodation hole;

a magnetic core, and a power-generating coil wound around the magnetic core, the magnetic core, stator and rotor constituting a first magnetic circuit, and a part of the stator around and adjacent to the rotor constituting a second magnetic circuit; and

further comprising a protrusion projecting toward the rotor formed on the inner periphery of the rotor accommodation hole of the stator within an angular range of ±

45°

around a magnetic flux direction of the first magnetic circuit at a rotation center of the rotor; and

a processor actuated by an electric energy generated by the power generator.

7. A power generator comprising:

a rotor having a permanent magnet rotated by a transmitted rotary drive force;

a stator having a rotor accommodation hole, the rotor being disposed in the accommodation hole;

a magnetic core, and a power-generating coil wound around the magnetic core, the magnetic core, stator and rotor constituting a first magnetic circuit, and a part of the stator around and adjacent to the rotor constituting a second magnetic circuit; and

further comprising a protrusion projecting toward the rotor formed on the inner periphery of the rotor accommodation hole of the stator within an angular range of ±

45°

around a magnetic flux direction of the second magnetic circuit at a rotation center of the rotor.

8. The power generator according to claim 7, wherein the protrusion is formed within an angular range of ±

10°

around the magnetic flux direction of the second magnetic circuit at the rotation center of the rotor.

9. The power generator according to claim 8, wherein the protrusion is formed in the magnetic flux direction of the second magnetic circuit at the rotation center of the rotor.

10. The power generator according to claim 7, further comprising an oscillating weight, and a power-generating gear train that provides said transmitted rotary drive force to the rotor by transmitting a rotation of the oscillating weight.

11. A timepiece comprising:

a power generator comprising;

a rotor having a permanent magnet rotated by a transmitted rotary drive force;

a stator having a rotor accommodation hole, the rotor being disposed in the accommodation hole;

a magnetic core, and a power-generating coil wound around the magnetic core, the magnetic core, stator and rotor constituting a first magnetic circuit, and a part of the stator around and adjacent to the rotor constituting a second magnetic circuit; and

further comprising a protrusion projecting toward the rotor formed on the inner periphery of the rotor accommodation hole of the stator within an angular range of ±

45°

around a magnetic flux direction of the second magnetic circuit at a rotation center of the rotor;

a time display; and

a processor for actuating said time display by an electric energy generated by the power generator.

12. An electronic device comprising:

a power generator comprising;

a rotor having a permanent magnet rotated by a transmitted rotary drive force;

a stator having a rotor accommodation hole, the rotor being disposed in the accommodation hole;

a magnetic core, and a power-generating coil wound around the magnetic core, the magnetic core, stator and rotor constituting a first magnetic circuit, and a part of the stator around and adjacent to the rotor constituting a second magnetic circuit; and

further comprising a protrusion projecting toward the rotor formed on the inner periphery of the rotor accommodation hole of the stator within an angular range of ±

45°

around a magnetic flux direction of the second magnetic circuit at a rotation center of the rotor; and

a processor actuated by an electric energy generated by the power generator.